Roles of the anterior cingulate cortex and medial thalamus in short-term and long-term aversive information processing.

Background: The anterior cingulate cortex (ACC) and medial thalamus (MT) are two of the main components of the medial pain pathway that subserve the affective aspect of pain. The hypothesis of the present study was that the ACC is involved in short-term aversive information processing and that the MT is critical for encoding unconditioned nociceptive information. The roles of these two components in short-term and long-term aversive information processing was investigated using a step-through inhibitory avoidance task.

Anxiety- and depressive-like responses and c-fos activity in preproenkephalin knockout mice: oversensitivity hypothesis of enkephalin deficit-induced posttraumatic stress disorder.

The present study used the preproenkephalin knockout (ppENK) mice to test whether the endogenous enkephalins deficit could facilitate the anxiety- and depressive-like symptoms of posttraumatic stress disorder (PTSD). On Day 1, sixteen wildtype (WT) and sixteen ppENK male mice were given a 3 mA or no footshock treatment for 10 seconds in the footshock apparatus, respectively. On Days 2, 7, and 13, all mice were given situational reminders for 1 min per trial, and the freezing response was assessed.

Nocifensive behaviors components evoked by brief laser pulses are mediated by C fibers.

Nocifensive behavior involves several response elements that have been used to assess neuropharmacological effects in different animal models of pain. Our previous analysis of laser-evoked nocifensive behaviors suggested that hierarchically organized responses in the nocifensive motor system are recruited in varying degrees by noxious stimuli of different intensities. Nocifensive behaviors can be differentially elicited and mediated by different classes of nociceptors.

A quantitative method for assessing of the affective component of the pain: conditioned response associated with CO2 laser-induced nocifensive reaction.

Sensory and affective components are included in the overall behavioral manifestation in a nocifensive reaction. We have developed a behavioral model using classical conditioning to differentiate the affective component from the sensory responses following a thermal noxious stimulus. In laser-pain conditioning, free moving rats were trained to associate a tone (conditioned stimulus, CS) and short CO2 laser pulsation (unconditioned stimulus, US).

Contribution of the anterior cingulate cortex to laser-pain conditioning in rats.

The emotional component of nociception is seldom distinguished from pain behavioral testing. The aim of the present study was to develop a behavioral test that indicates the emotional pain responses using the classical conditioning paradigm. The role of the anterior cingulate cortex (ACC) in the process of this pain conditioning response was also evaluated.

Potentiation of local field potentials in the anterior cingulate cortex evoked by the stimulation of the medial thalamic nuclei in rats.

The limbic thalamus and cingulate cortex are essential components in mediating the affective component of pain responses. In the present study, we examined the excitatory properties of medial thalamus (MT)-evoked field potentials in the anterior cingulated cortex (ACC). We also examined the effects of paired pulses and brief tetanic stimuli of the MT.